Acquiring and Targeting Heat Exposures Necessary for Action

NCT05678738 | Completed

• 2 other identifiers: H21-0108BA200299
• Study Type: interventional
• Target: 108
• Locations: 1 country
• Sites: 1

Brief Summary

The purpose of this research study is to better understand ways that women and men differ physiologically, cognitively, physically, and cellularly to better prescribe helpful interventions that will prevent injury and risk of conditions like exertional heat illnesses or heatstroke. The main questions this project aims to answer are:

1. 1.What is the relative stress contributing to performance differences between women and men during intense exercise in extremely hot and humid environments in response to exertional heat stress?
2. 2.What is the relative contribution of responses in adipose tissue, cardiovascular tissue, gut microbiota, and musculoskeletal tissue on heat tolerance in women (vs. men) to exertional heat stress?
3. 3.What is the impact of adding an antioxidant juice consumption regime and will it assist in enhancing performance during an acute bout of exercise-heat stress before and after heat acclimation?
4. 4.a heat acclimation protocol which includes the completion of 5 days of prescribed exercise-heat exposure
5. 5.two separate acute exercise-heat exposures for the assessment of thermotolerance and the investigation of potential enhancements in thermoregulatory performance that may occur after the completion of a 5-day heat acclimation protocol
6. 6.a subset of subjects enrolled and approved for participation who opt in to antioxidant berry supplement consumption will either consume the active or placebo product throughout their participation.

Conditions

Heat Intolerance; Heat Stress; Fatigue; Heat

Keywords

Sex Differences; Physical Performance; Body Composition; Heat Acclimation

Outcome Measures

Primary Outcomes (41)

• Change in Rectal Temperature at Rest

  Rectal thermometer will be self-inserted by participants to assess core temperature prior to exercise-heat stress bouts

  Through study completion, an average of 14 days

• Change in Rectal Temperature Rate of Rise

  Rectal thermometer will be self-inserted by participants to assess core temperature during exercise-heat stress bouts

  Through study completion, an average of 14 days

• Change in Rectal Temperature at Thermal Threshold (38.5C)

  Rectal thermometer will be self-inserted by participants to assess core temperature during exercise-heat stress bouts at the thermal threshold of 38.5C

  Measured throughout 5 90-minute exercise-heat stress bouts (heat acclimation sessions)

• Change in Mean Skin Temperature

  Prior to start of exercise, participants will be instrumented with iButton skin temperature sensors on the chest, shoulder, abdomen, neck, back, thigh, and calf

  Through study completion, an average of 14 days

• Change in Heart Rate

  A heart rate monitor will be worn by participants throughout the exercise-heat stress bouts

  Through study completion, an average of 14 days

• Change in Heart Rate at Thermal Threshold (38.5C)

  A heart rate monitor will be worn by participants throughout the exercise-heat stress bouts to assess HR at the thermal threshold of 38.5C

  Measured throughout 5 90-minute exercise-heat stress bouts (heat acclimation sessions)

• Change in Whole Body Sweat Rate

  Difference in body weight measurement measured prior to and at the cessation of each exercise-heat stress bout

  Measured at the beginning and end of 5 90-minute exercise-heat stress bouts (heat acclimation sessions)

• Change in Sweat Metabolite and Protein Expression

  Sweat samples will be collected and assessed for metabolite and protein expression discovery via mass spectrometry

  Measurement completed during each exercise-heat stress bout (Heat Tolerance Tests 1 [days 5 and 12] and 2 [days 6 and 13]) both before and immediately after heat acclimation as well as the final heat acclimation session (HA5 - day 11)

• Change in Cognitive Measures - Visual Vigilance

  Participants will perform an assessment of visual vigilance through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion

  Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Cognitive Measures - Psychomotor Vigilance

  Participants will perform an assessment of psychomotor vigilance through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion

  Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Cognitive Measures - Four Choice Task

  Participants will perform an assessment of four choice task success through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion

  Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Cognitive Measures - Match to Sample

  Participants will perform an assessment of match to sample success through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion

  Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Cognitive Measures - Repeated Acquisition

  Participants will perform an assessment of repeated acquisition through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion

  Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Cognitive Measures - Grammatical Reasoning

  Participants will perform an assessment of grammatical reasoning through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion

  Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Cognitive Measures - Profile of Mood States

  Participants will perform an assessment of profile of mood states through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion

  Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Cognitive Measures - Stroop Task

  Participants will perform an assessment of stroop task success through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion

  Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Physical Performance - Anaerobic Performance

  Participants will be assessed for anaerobic performance with the completion of a 400 meter sprint for time. This test is part of a larger physical performance battery test which should take approximately 30 minutes for completion

  Measurements completed immediately after the cognitive battery performed during the Heat Tolerance Test 2 (days 6 and 13) both before and immediately after heat acclimation

• Change in Physical Performance - Agility Performance

  Participants will be assessed for anaerobic performance with the completion of a quick feet agility test. This test is part of a larger physical performance battery test which should take approximately 30 minutes for completion

  Measurements completed immediately after the cognitive battery performed during the Heat Tolerance Test 2 (days 6 and 13) both before and immediately after heat acclimation

• Change in Physical Performance - Upper Body Strength Performance

  Participants will be assessed for upper body strength performance with the completion of a handgrip strength test. This test is part of a larger physical performance battery test which should take approximately 30 minutes for completion

  Measurements completed immediately after the cognitive battery performed during the Heat Tolerance Test 2 (days 6 and 13) both before and immediately after heat acclimation

• Change in Physical Performance - Lower Body Power Performance

  Participants will be assessed for lower body power performance with the completion of a vertical jump test. This test is part of a larger physical performance battery test which should take approximately 30 minutes for completion

  Measurements completed immediately after the cognitive battery performed during the Heat Tolerance Test 2 (days 6 and 13) both before and immediately after heat acclimation

• Change in Physical Performance - Lower Body Kinematic Performance

  Participants will be assessed for lower body kinematic performance with the completion of the Landing Error Scoring System (LESS) Test. This test is part of a larger physical performance battery test which should take approximately 30 minutes for completion

  Measurements completed immediately after the cognitive battery performed during the Heat Tolerance Test 2 (days 6 and 13) both before and immediately after heat acclimation

• Change in Physical Performance - Balance Performance

  Participants will be assessed for balance performance with the completion of the Balance Error Scoring System (BESS) Test. This test is part of a larger physical performance battery test which should take approximately 30 minutes for completion

  Measurements completed immediately after the cognitive battery performed during the Heat Tolerance Test 2 (days 6 and 13) both before and immediately after heat acclimation

• Change in Musculoskeletal Gene and Protein Expression

  Musculoskeletal tissue samples will be collected for analysis via RNA-seq

  Measurement completed after the performance of an exercise-heat stress bout and physical performance battery (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Musculoskeletal Fiber-Typing

  Musculoskeletal tissue samples will be collected for fiber-type analysis via immunohistochemical procedures

  Measurement completed after the performance of an exercise-heat stress bout and physical performance battery (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Musculoskeletal Mitochondrial Function

  Musculoskeletal tissue samples will be collected for analysis of mitochondrial function

  Measurement completed after the performance of an exercise-heat stress bout and physical performance battery (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Subcutaneous Abdominal Tissue (SCAAT) Lipolysis Rate

  SCAAT lipolysis rate (interstitial glycerol and ethanol output:input) will be collected and assessed for fat mobilization and subcutaneous adipose tissue blood flow during exercise-heat stress bouts

  Measurement completed after the performance of an exercise-heat stress bout and physical performance battery (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Resting Energy Expenditure and Macronutrient Oxidation

  Participant resting energy expenditure, fat oxidation, and carbohydrate oxidation will be assessed via indirect calorimetry for the measurement of respiratory quotient and respiratory exchange ratio

  Measurement completed after the performance of an exercise-heat stress bout and physical performance battery (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation

• Change in Circulatory Indicators of Lipid Metabolism - NEFAs

  Blood samples will be collected and assessed for the expression of lipid metabolism biomarker Non-Essential Fatty Acids (NEFAs)

  Throughout study completion, an average of 14 days

• Change in Circulatory Indicators of Lipid Metabolism - Insulin

  Blood samples will be collected and assessed for the expression of lipid metabolism biomarker Insulin

  Throughout study completion, an average of 14 days

• Change in Circulatory Indicators of Lipid Metabolism - IGF-1

  Blood samples will be collected and assessed for the expression of lipid metabolism biomarker Insulin Growth Factor-1 (IGF-1)

  Throughout study completion, an average of 14 days

• Change in Circulatory Indicators of Stress - Epinephrine

  Blood samples will be collected and assessed for the expression of physiological stress biomarker Epinephrine

  Throughout study completion, an average of 14 days

• Change in Circulatory Indicators of Stress - Norepinephrine

  Blood samples will be collected and assessed for the expression of physiological stress biomarker Norepinephrine

  Throughout study completion, an average of 14 days

• Change in Circulatory Indicators of Stress - Cortisol

  Blood samples will be collected and assessed for the expression of physiological stress biomarker Cortisol

  Throughout study completion, an average of 14 days

• Change in Circulatory RNA Content

  Blood samples will be collected and assessed for intracellular RNA content

  Throughout study completion, an average of 14 days

• Change in Circulatory Indicators of Inflammation - IL-1B

  Blood samples will be collected and assessed for the expression of inflammatory biomarker IL-1B

  Measurement completed during the completion of exercise-heat stress bouts (Heat Tolerance Tests 1 [days 5 and 12] and 2 [days 6 and 13]) both before and immediately after heat acclimation

• Change in Circulatory Indicators of Inflammation - TNF-a

  Blood samples will be collected and assessed for the expression of inflammatory biomarker TNF-a

  Measurement completed during the completion of exercise-heat stress bouts (Heat Tolerance Tests 1 [days 5 and 12] and 2 [days 6 and 13]) both before and immediately after heat acclimation

• Change in Circulatory Indicators of Inflammation - IFN-gamma

  Blood samples will be collected and assessed for the expression of inflammatory biomarker IFN-gamma

  Measurement completed during the completion of exercise-heat stress bouts (Heat Tolerance Tests 1 [days 5 and 12] and 2 [days 6 and 13]) both before and immediately after heat acclimation

• Change in Gut Microbiome Diversity

  Stool samples will be collected and assessed for the impact of gut microbiome diversity on heat intolerance

  Measurement completed prior to the completion of an exercise-heat stress bout (Heat Tolerance Test 2) both before and after heat acclimation

• Change in Saliva Metabolite Expression

  Saliva samples will be collected and assessed for metabolite expression

  Measurement completed during each exercise-heat stress bout (Heat Tolerance Tests 1 and 2) both before and after heat acclimation as well as the final heat acclimation session (HA5)

• Change in Thermal Sensation

  0-8 Scale (cold to hot) that indicated how cold or hot the participant feels. 0 = extremely cold, 8 = extremely hot

  Through study completion, an average of 14 days

• Change in Recovery

  Participants will be provided a WHOOP strap after the completion of their baseline visit and will be instructed on how to download the associated application and use of the device. The WHOOP device will be used to provide data on sleep quality and quantity, strain, and recovery

  Throughout study completion, an average of 14 days

Secondary Outcomes (12)

• Change in Perception of Fatigue

  Throughout study completion, an average of 14 days

• Change in Perception of Thirst

  Throughout study completion, an average of 14 days

• Change in Environmental Perception

  Throughout study completion, an average of 14 days

• Change in Rating of Perceived Exertion

  Throughout study completion, an average of 14 days

• Change in Sleep Quality

  Throughout study completion, an average of 14 days

Study Arms (3)

Acute and Chronic Exercise-Heat Stress

EXPERIMENTAL

All participants (male and female) will be exposed to repeated bouts of exercise-heat stress.

Other: Acute and Chronic Exercise-Heat Stress

Exercise-Heat Stress + Antioxidant Berry Supplementation

ACTIVE COMPARATOR

All participants (male and female) will be exposed to repeated bouts of exercise-heat stress. Participants who opt-in may be randomly assigned to receive bioactive (antioxidant berry supplement) ingredient in addition to repeated bouts of exercise-heat stress.

Dietary Supplement: Antioxidant Berry Supplementation; Other: Acute and Chronic Exercise-Heat Stress

Exercise-Heat Stress + Placebo (Non-juice) Supplementation

PLACEBO COMPARATOR

All participants (male and female) will be exposed to repeated bouts of exercise-heat stress. Participants who opt-in may be randomly assigned to receive placebo (non-juice) ingredient in addition to repeated bouts of exercise-heat stress.

Other: Acute and Chronic Exercise-Heat Stress; Dietary Supplement: Placebo (non-juice) Supplementation

Interventions

Antioxidant Berry Supplementation DIETARY_SUPPLEMENT

Participants who opt-in will be instructed to consume 300mL of the bioactive (antioxidant berry) supplement every morning and afternoon during days of participation.

Exercise-Heat Stress + Antioxidant Berry Supplementation

Acute and Chronic Exercise-Heat Stress OTHER

All participants (male and female) will be exposed to repeated bouts of exercise-heat stress.

Acute and Chronic Exercise-Heat Stress; Exercise-Heat Stress + Antioxidant Berry Supplementation; Exercise-Heat Stress + Placebo (Non-juice) Supplementation

Placebo (non-juice) Supplementation DIETARY_SUPPLEMENT

Participants who opt-in will be instructed to consume 300mL of the placebo (non-juice) supplement every morning and afternoon during days of participation.

Exercise-Heat Stress + Placebo (Non-juice) Supplementation

Eligibility Criteria

• Age: 18 Years - 50 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• The target composition of our subject sample is 50% men and 50% women.
• No difficulties with vision, hearing, or ability to read a computer screen and operate a computer keyboard and mouse.

You may not qualify if:

• unable to visit the laboratory on the required, consistent schedule and consecutive required days (Days 2 and 3, Days 12 and 13)
• any contraindications to participating in exercise lasting 60-120 minutes daily during a period of 2 consecutive days, 5 days within an 8-day period, and 2 additional days (if subjects elect to participate in the entire study, all options), screening will include resting blood pressure to exclude pre-hypertensive or hypertensive participants (resting BP \> 120 mmHg and 80mmHg systolic and diastolic, respectively)
• any contraindications to exposure to exercise-heat stress (e.g., medications that affect thermoregulation, family or personal history of issues with anesthetics that indicate possible susceptibility to malignant hyperthermia, evidence of past heat intolerance)
• tobacco use or electronic cigarettes (e-cigarettes) within the past 6 months
• chronic illness (including diabetes, metabolic syndrome, thyroid disease, for example) or other chronic illnesses that make it unsafe for participants to participate in daily rigorous exercise in the heat
• regular supplementation with blood thinners, including the use of aspirin
• acute illness (e.g., influenza, head cold, gastrointestinal illness) during the week of scheduled testing
• current positive COVID-test or infection and past COVID infection within past 6 months
• contraindications to blood draw and if elected to be considered for participation with microdialysis and skeletal muscle biopsy procedures, contraindications to those individual procedures
• for subjects who may not complete a DXA scan, history of claustrophobia
• history of allergic reactions to medical tape and/or latex
• currently participating in "non-traditional" diets including diets such as intermittent fasting, caloric restriction, highly limited consumption of large food classes (e.g., vegan)
• consumption of antioxidant supplementation on a regular, long-term basis outside of the aronia supplementation regime for the study
• limited decision-making ability
• inability to participate in extended physical activity on a treadmill (i.e., standing, running, jogging, walking)

Sponsors & Collaborators

• University of Connecticut: lead
• United States Department of Defense: collaborator

Study Sites (1)

Human Performance Laboratory at the University of Connecticut

Storrs, Connecticut, 06269, United States

Location

MeSH Terms

Conditions

Heat Stress Disorders

Interventions

Dietary Supplements

Condition Hierarchy (Ancestors)

Wounds and Injuries

Intervention Hierarchy (Ancestors)

Food; Diet, Food, and Nutrition; Physiological Phenomena; Food and Beverages

Study Officials

• Douglas J Casa, PhD

  Korey Stringer Institute - UConn

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Masking Details: Participants who opt-in for antioxidant berry supplementation will be randomly assigned to either the group receiving the bioactive ingredient (berry fruit juice) or the placebo group. Both groups will receive 300mL to consume every morning and afternoon during participation.
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Model Details: Participants will consist of both male and female subjects who will be exposed to similar bouts of exertional heat stress. Analysis will be completed to assess for potential sex-based differences in outcomes measured (male vs. female). Participants (both male and female) who opt-in for antioxidant berry supplementation will be assigned to a subgroup parallel study model where subjects will be exposed to similar bouts of exertional heat stress while consuming either the antioxidant or placebo supplement.

Study Record Dates

• First Submitted: December 16, 2022
• First Posted: January 10, 2023
• Study Start: September 16, 2021
• Primary Completion: April 17, 2024
• Study Completion: April 17, 2024
• Last Updated: September 11, 2025

Record last verified: 2025-09

Locations

US (1)